Bug: Failed to obtain port for Reloaded instance running inside the process.
[ My P4G mods installed as only: Yosuke Romance, P4GPC Freecam, CRI FileSystem V2 Hook, and Persona Essentials. Wasnt able to use any mods when I started to play. Thanks in advance.
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Try Edit Application -> Deploy ASI Loader.
Then start game from Steam
I'm also having this issue. Completely fresh install of Persona 5 Royal. Completely fresh Reloaded-II install with absoultely no remnants of older installs whatsoever. All prerequisites properly installed. Computer restarted. Mods downloaded directly from the mod downloader section. Attempting to launch the game locks up the program for 10 seconds then crashes with the same error OP is getting.
It does actually create the game process, but leaves it open in the background when it fails.
Sewer56's proposed solution does not work, as that results in the game hanging on a black screen. Older (est. 2 years ago, so not too helpful) versions of Reloaded-II worked perfectly.
Edit: After doing some more testing, I can confirm that this issue is not on my end. I launched the game 50 times in a row using each method - shortcut, "Launch Application" option, and ASI Loader. Shortcut and "Launch Application" option successfully launched 2 times out of the 50 launch attempts each. ASI Loader hung a black screen all 50 launches. There's no way the issue is on my end. Additionally, the few times the program worked properly, quitting out of the game using the game's own "quit to desktop" feature caused it to crash instead, and with a default Windows "P5R.exe has stopped working" error which never happened on older versions. None of these happen for me in the normal game without Reloaded-II.